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Discussion Starter #1
Hey everyone~



I know there is some great dual sprocket info on the old site but all the pics are gone and it makes it really challenging the visualize things.

So, I propose we make this into the new Dual Sprocket thread where we can have all that info in one spot.

There are different approaches and ideas for this subject.

Here are a few: (I sourced the photos from various threads... hope that's ok)

1. 1 front sprocket / 2 rear sprockets


2. 2 front sprockets / 2 rear sprockets


3. 1 front sprocket / 1 rear sprocket w/ outer bolt-on ring of teeth.




I just upgraded to 14/47 and o-ring chain. I already miss the lower gearing. So I am planning to do some sort of dual sprocket setup...



Please help build this thread into a great info source on this subject!
 

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Nicely presented... In my opinion, there are a few considerations.



1) How much work do you want to put into the mod?



2) How much money do you want to put into this mod?



3) How much time do you want to spend doing a ratio change......... Gerry
 

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The dual front and rear sprockets are 'unique'. You can do it all yourself (I did on the 1st set) but likely, you would seek out a machinist and that would add to the cost.



The advantage of the dual/dual sprocket mod is, you get a "very fast" 6 tooth spread in about as much time as it takes to lossen the rear axle nut. No chain length change is needed if you stay with the six tooth spread (one front, five rear). Of course, you need a wrench and would be inclined to get the rear wheel off the ground so it can be rotated. These issues would be the case with both approaches.



The disadvantage of the dual/dual set-up is it's uniqueness. The second primary sprocket is not held in place by splines on the shaft, it is mated to the stock sprocket and held by two grade 12, 8mm allen bolts and 4 tempered 'coil pins' (very strong). Should you be an aspiring hot-dog Moto-Cross kind of rider, it is anyones guess if bolts and pins will hold. It has worked fine for me for a couple of years.



For reasons that I can not explain, I generally move towards the bazaar. I have only switched ratios once when I was to do a longish pavement ride into the mountains. The change was fast, simply slacken the chain and roll it onto the adjacent sprocket set.



My opinion; I like what I did alot. I took an idea and followed it thru to the point of success, I feel proud.



As well, the overlay sprocket is tried and true........ Likely you won't need it often so fast is not really an issue. The overlay affords you a much wider range of ratios, all you need is to be willing to spend the extra time to add/remove an extra length of chain. Think it over before you decide..... Gerry



{some more pictures} http://photobucket.com/mrgizmow
 

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Discussion Starter #5
OK, I chose option #2 for simplicity...



So, I'm running:



Front: 14-tooth JT sprocket

Rear: 47-tooth & 50-tooth JT sprockets. (note: these sprockets have a machining to them, in that there's a recessed area where the mounting holes are)

Custom fitted DID 428 o-ring chain. I'll have to count the links later...



To switch between them, all you have to do is loosen the axle nut, loosen the adjusters, put the chain on the other sprocket, tighten the adjusters, and tighten the axle nut and reinstall cotter-pin. You should also confirm the rear brakes are adjusted properly. Total time to switch gears is easily under 5 minutes.



The spacing worked out perfect. I'm surprised at how well the chain looks on either gear.



For me, I'll usually run on the 50-tooth (bombing around town and running trails). But, when a longer distance ride is in store, a quick change-over will make cruising at 55-60 no problem.



OK, here are some pics:




This is a quick diagram to show the hardware used for the 6 bolts...





Here are some different views of the dual rear sprockets: (note: blue color on 6 bolts is lock-tite)





 

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Looks good. Keep an eye on chain tension and in my opinion, you should never have a problem. If you want to keep it, with some slight modding, you can still use the chain guard. It's kind of neat to see someone adopt one of my 'unique' ideas. Gerry
 

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Discussion Starter #7
Thanks mrgizmow!


I knew I wanted to have 2 sprockets as soon as I saw your custom work...

Then, after trying both 47 & 50 tooth rear sprockets seperately, it had to be done. I wanted both gear sets available with a quick change.

Thanks again for your inspiration and ideas!
 

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So are there any long term negative effects of this set up? Or is the difference in the angle of the chain to minor to cause problems?
 

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I will add some insights as I may have more miles on mine than Darnold87. There seems to be give and takes with most mods. After a couple of thousand miles I did note some marking on the teeth of the slightly mis-aligned sprocket, but not enough to suggest that a sprocket replacement in 10,000 mile VS 15,000 would be an issue for "me". In my opinion, sprockets and medium quality chains are so reasonably priced as to make this concern a non-issue. For me, the important issue is flexibility. There are lots of posts on this forum regarding gearing. As a dual-sport bike, the stock setup seems to represent some middle ground. With the dual sprockets, you are able to move a 'bit' closer to prefect. If 'slight' mis-alignment is a major concern, you can spend a bit more time and money by adding a second primary sprocket. With the 4 sprockets (2 unique gear sets) you can get perfect alignment with each combo as each sprocket set will be spaced the same distance apart.



Anytime you mod from stock, there is always (in my opinion) a chance for some nasty unforeseen issue to develop that could compromise your safety. Use care and think about what you are doing. Gerry
 

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Discussion Starter #13
Basically same idea as my 1964 Honda Trail 90 from the factory, except for the dual front sprockets.


Exactly... those had much more variance between to the two rear sprockets right? A small one and a huge one? Which also required adding a sectrion of chain? That's what I've heard anyway.

I may add a larger rear sprocket someday, but it's nice having the rear sprockets be similar enough in size to not require adding a section of chain. Simple-Simple.
 

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I've run wheel sprockets with a difference of 4 teeth without having to mess with chain length. Not much room in the adjustment slot for more than that.
 

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I've run wheel sprockets with a difference of 4 teeth without having to mess with chain length. Not much room in the adjustment slot for more than that.


Qwerty, I will say, you are likely correct. There is however, ample room to elongate the slot. In my opinion, when a mod option is presented, the modder needs to be aware that 'he' may need to deal with a few "unstated issues." If memory serves, I did indeed move (increase) the slot forward. As well, I modified the chain adjusting cams to afford me more slack when loosening the chain. Gerry
 

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Funny story about the Honda 90, I forget if I read it here or somewhere else. When Honda first released the 90, there was a dealer in California who would modify them with 70 tooth sprockets and grip tires, They did great in the foothills with these mods, the things would fly out the door. So when the Honda brass took notice of why this dealer was selling more Honda 90's than anyone else, they immediately dispatched some eggheads to figure out why. Their response was the dual range sub transmission.



LOL, times have changed so much, do you think Honda would give it's customers the time of day in 2010? They'd probably respond by pulling the dealers license over liability issues....
 

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I want to run a 55/70 combo on mine, but I'm a bit concerned about the unsplined area on the front shaft.



I'm gunna look into one-piece industrial double sprockets for the front. Anyone already beaten that horse?
 

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Is there a downside to just adding a small section of chain to avoid having to loosen and adjust the rear tire every time you change which sprocket you drive?
 

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My ability to recall "exactly" has been somewhat compromised, likely a genetics thing as my Father would offten forget my name. In my opinion, should you be willing to pay a machinist, you should be able to get your 'secondary' primary sprocket indexed with as many coil pins (strong) as you want. I believe the stock shaft provides 6 'teeth'. Unless you are big guy, and plan to race, in my opinion, you should be able to make your 'sister' sprocket attachment "strong" enough.



Nothing wrong with adding extra length of chain to get an even wider spread in your ratio options. There will be a few opinions on this to be sure. No matter if you boughht your bike new (me) or bought used. To me, the TW is a simple and inexpensive bike, parts like sprockets and chains are very affordable. Certainly, mis-matching components that have been subject to different degrees of wear would not represent the 'ideal', but in my opinion, nothing about the bike was made to represent the 'ideal'.



Certainly, all of the above represent 'less' than optimum conditions (factory stock). I have mentioned before, my main concerns are (1) SAFETY and (2) convenience.



I tried the wider spread (gearing) with the added section of chain. For me, this added enough time (not much) and energy to the ratio switch, as to suggest I would not be inclined to fuss with adding/subtracting chain sections to achieve my goals. You still need to loosen and re-tighten the axle to put in place the new section of chain and get it properly tensioned..



In just dealing with the rear sprocket I am of the opinion that any 5 tooth spread is available. Here are some examples; should you be primarily a street commuter, but like trails, try a 45/50 rear combo. If you (like me) are into back country exploring, how about 50/55. Now in changing the front as well, offers an even greater spread.



I am not selling anything, but am certainly pleased when someone gleens value from my ramblings. There are a few that continue to 'walk the planet' because they don't trust flying machines. Study well, and use whats available to your benefit. Sounds good to me, Gerry



 
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